Why is my Mercedes-Benz E-Class leaking transmission fluid from underneath after parking overnight?

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Why is my Mercedes-Benz E-Class leaking transmission fluid from underneath after parking overnight?

Many E-Class owners in Pakistan notice reddish o r brown fluid pooling under the car after it has been parked overnight. This is often seen in older models like the W211 and W212. Could this be due to worn-out seals, oil pan gasket failure, o r bad workmanship during past servicing? How can you confirm if the leak is from the transmission and not the engine?

Talha Kyanii asked on 11 Oct 2025 12:56:31 pm

1 Answer

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Gari Master - on 11 Oct 2025 12:58:31 pm

If you notice reddish-brown fluid under your E-Class after parking, it’s likely leaking ATF Automatic Transmission Fluid. This is especially common in older models like the W211 and W212, and can be caused by:

Worn transmission oil pan gasket – usually due to age o r heat exposure.

Leaking transmission drain plug o r bolts – often caused by overtightening o r improper sealing during service.

Old o r cracked transmission seals e.g., output shaft seal o r input seal.

In Pakistan, extreme heat and poor roads accelerate gasket wear. Additionally, oil leaks are often misdiagnosed as engine oil leaks due to similar appearance and location.

What to do:

Confirm its ATF reddish/brown, smooth feel and not engine oil.

Inspect around the transmission oil pan and gasket.

Have a trusted mechanic perform a pressure test o r dye test to find the exact source.

Replace gaskets o r seals only with OEM parts, and avoid silicone sealants unless recommended.